ASME SA 333 Grade 6 Carbon Steel Seamless Pipe
Dec 05, 2025
What Is A333 Gr.6 Pipe
A333 Gr.6 is a low-temperature seamless steel pipe that complies with the ASTM A333/ASME SA333 standard, primarily used in environments at about minus 45 deg C and above. Its chemical composition is specially designed: it is a silicon-killed carbon-manganese steel with a fine-grain normalized structure. Note that Grade 6 contains no nickel requirement; it achieves low-temperature toughness through grain refinement and deoxidation rather than alloying, which is why it is more economical than the nickel grades. The steel pipe is manufactured through hot rolling or cold drawing processes, ensuring a uniform internal structure free from welding defects. Being seamless, it offers greater reliability under high pressure compared with welded pipe, making it particularly suitable for piping systems in low-temperature service conditions.
Chemical Composition (Max)
| Element | Grade 6 |
|---|---|
| Carbon | 0.30 |
| Manganese | 0.29-1.06 |
| Phosphorus | 0.025 |
| Sulfur | 0.025 |
| Silicon | 0.10 min |
| Nickel | Not required |
Mechanical Properties
| Property | Data |
|---|---|
| Tensile strength, min | 415 MPa |
| Yield strength, min | 240 MPa |
| Elongation, min (longitudinal/transverse) | 30 / 16.5 percent |
Applications
Liquefied natural gas (LNG) plants and the low-temperature sections of gas processing facilities: low-temperature steel pipe is a core material for low-temperature media transfer within the grade temperature limit. Petrochemical industry: processes that require low-temperature operation, such as storage and transportation of ethylene and liquid ammonia, within the design class. Refrigeration equipment: piping in industrial refrigeration systems, especially components that operate at low temperatures for extended periods. For service below the minus 45 deg C class, nickel grades such as Gr.3 or Gr.8 must be selected.
Testing and Inspection
Standard inspection includes tensile testing, Charpy impact testing at the specified low temperature, hydrostatic testing, and non-destructive testing as required, with the mill test certificate documenting the results.
Frequently Asked Questions
Q: What is SA333 Gr.6 pipe? A> A low-temperature seamless carbon steel pipe per ASME SA333 for service at about minus 45 deg C and above.
Q: Does Gr.6 contain nickel? A> No. It is a silicon-killed carbon-manganese steel; the nickel grades are Gr.3 and Gr.8.
Q: What are the mechanical properties? A> Tensile 415 MPa min, yield 240 MPa min, elongation 30/16.5 percent.
Q: Why is seamless preferred? A> No longitudinal weld gives greater reliability under high pressure in low-temperature service.
Q: Where is Gr.6 used? A> LNG plants, petrochemical low-temperature processes, and industrial refrigeration systems.
Q: Can Gr.6 handle minus 100 deg C? A> No. That range requires the nickel grades.
Need SA333 Gr.6 seamless pipe for your low-temperature system? Contact us with your size and specification for a quotation.
